Abstract

CARVALHO, A. N.  and  SANTOS, P. T.. Factors affecting the distribution of epibenthic biodiversity in the Cávado estuary (NW Portugal). RGCI [online]. 2013, vol.13, n.1, pp.101-111. ISSN 1646-8872.  https://doi.org/10.5894/rgci371.

The epibenthic fauna of the lower Cávado estuary at five sampling stations was studied over a period of two years. We examined the spatial and seasonal distribution of different species and analysed temperature, salinity, dissolved oxygen, precipitation and sediment type, which are all important features of estuarine dynamics. A total of 15 taxa were identified. Crustaceans had the highest levels of abundance (91%) and biomass (87%). Crangon crangon was the most abundant species (75%) and Carcinus maenas had the highest biomass (71%). No exotic species were recorded. Multivariate analysis showed two different spatial assemblages, one corresponding to stations nearest to the mouth (higher abundance values) and other to the upstream stations. The Shannon diversity index was highest at the margin station further upstream. Three different assemblages could be distinguished, separating summer/autumn (higher values of abundance) from spring and from winter. According to BIOENV analysis, dissolved oxygen, water temperature and salinity were the environmental variables responsible for the spatial and seasonal distribution of epibenthos, explaining 17.2% of variability. Abundance and biomass were better correlated with water temperature. Sediment type was also important in epibenthic spatial distribution, being abundance, biomass and diversity indexes better correlated with fine sediment (<0.125mm).

Keywords : epibenthos; estuarine ecosystem; diversity; environmental variables.

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